This amazing project provides a ready-to-use Docker configuration to start a Samba server for OPL.
https://github.com/milouk/docker-smb-opl
Once you have Free MCBoot on your PS2, you have multiple ways to load and play backed-up games. Samba is probably the easiest way to add or remove games, as you can simply upload or place games in a folder shared via Samba. The PS2 can then load games from that Samba share. The problem is that OPL requires a rather outdated and insecure version of Samba, which is not a good idea to enable on your modern Windows PC. With this Docker method, you can start a virtualized server dedicated to this purpose. It is easy (if you have used Docker before) and secure.
bin/cue to iso
OPL can only read .iso files. If the game is in bin/cue format, you can use bchunk to convert it.
You can install bchunk with Homebrew on macOS:
brew install bchunk
To convert, use filenames like this:
bchunk Gradius\ V\ \(USA\).bin Gradius\ V\ \(USA\).cue Gradius\ V\ \(USA\).iso